In­sight

Bring on the apoc­a­lypse, the Si­len­thawk has your back

there’s al­ways been a cliché that all of the coolest tech­nol­ogy mankind has come up with is hid­den by the gov­ern­ment or mil­i­tary. As it hap­pens, mo­tor­cy­cling is no dif­fer­ent. Meet the Si­len­thawk, built in a crevasse lo­cated some­where between mil­i­tary R&D and the mo­tor­cy­cling world, by an en­gi­neer­ing and sci­ence com­pany called Lo­gos Tech­nolo­gies. Es­sen­tially, it’s an Alta Red­shift MX ebike—a 270-pound, 40-hp, all-elec­tric mo­tocrosser built by Alta Mo­tors in Noth­ern Cal­i­for­nia— that’s been toyed with by some pretty smart peo­ple.

The key bit of kit that has been adapted is a pe­tro­leum-pow­ered, “genset range ex­ten­der.” It’s a tiny, liq­uid­cooled ro­tary en­gine, roughly the size of a grapefruit, weigh­ing about 10 pounds and crank­ing out around 15 hp and/or 6kw. That means charg­ing the bike’s 5.8kwh bat­tery in the stan­dard 2.5 hours at 240 volts (ex­clud­ing what­ever equip­ment is plugged in), as long as there’s some fuel in the two-gal­lon tank.

What kind of fuel? It ac­tu­ally doesn’t re­ally mat­ter. Kerosene, gaso­line, diesel, jet fuel—the en­gine doesn’t re­ally care; it just needs a heads up for what to ex­pect so it knows how to start. “Once the en­gine starts it will au­to­mat­i­cally reg­u­late it­self to all of that,” says Alex Dzwill, Lo­gos’ lead en­gi­neer for Si­len­thawk, adding ca­su­ally, “it has a re­ally com­pli­cated ECU.” Run­ning on any fuel is a key facet for the mil­i­tary so that sol­diers in the field can use what­ever they find. In­ter­est­ingly, Dzwill said that ef­fi­ciency isn’t af­fected by dif­fer­ent fuel.

The tech­nique of us­ing the com­bus­tion en­gine as a gen­er­a­tor rather than propul­sion is alive al­ready. It’s a very sim­i­lar sys­tem to the one used

in BMW’S i3 elec­tric car, which has an op­tion for a two-cylin­der en­gine to pump out elec­tric­ity and keep the bat­tery charged. Where the i3 is twowheel drive, the Si­len­thawk em­ploys a nifty trick to be­come all-wheel drive. It uses an in­de­pen­dent hub-pow­ered front wheel that is con­trolled by the bike and can de­liver up to 7 hp to the front con­tact patch. It’s a self­con­tained unit, driven sep­a­rately from the Alta mo­tor and rear wheel, and can be turned on or off by the rider.

ADV types will ap­pre­ci­ate that there are aux­il­iary plugs for equip­ment strewn all over the bike. It was de­signed for charg­ing com­mu­ni­ca­tion and nav­i­ga­tion equip­ment for mil­i­tary use, but then again the same goes for civil­ian rid­ers. An­other in­ter­est­ing slice of the hy­brid tech­nol­ogy on the Si­len­thawk is its abil­ity to au­to­mat­i­cally charge its bat­ter­ies and gear when it’s parked. Again, de­signed for mil­i­tary use (mostly as a com­mu­ni­ca­tion bea­con) so that the bike can recharge with­out be­ing rid­den or turned on. Phase two of this project is set to in­clude an air-cooled ro­tary en­gine that’s smaller and lighter, as well as up­dat­ing all of the pow­er­gen­er­a­tion hard­ware to be more com­pact and ef­fi­cient.

The po­ten­tial ap­pli­ca­tion for civil­ian use is clear to see. A hy­brid mo­tor­cy­cle that weighs 350 pounds, with a range of around 170 miles that will recharge it­self and any­thing you leave plugged into it while it sits in your park­ing lot at work is a pretty at­trac­tive propo­si­tion. Not to men­tion a lit­tle more fuel would add range and still be well un­der­weight for most mo­tor­cy­cles on the road to­day. Who knows what else they might have in the base­ment?

As reg­u­lar as the Si­len­thawk ap­pears, it in­cludes some unique tech­nol­ogy. The self-con­tained hub mo­tor in the front wheel, for one. The next ver­sion will likely have a con­trol screen rather than old-school switches.